Binders generally are comprised of two high-level assemblies, a "skeleton " and cover. The skeleton, as used herein, refers to the chassis of the binder, including the rings, spine and possible actuators, but excluding the cover. The spine, as used herein, refers to the elongated portion of the skeleton on which the rings are mounted; the spine excludes the rings, any transversely protruding elements disposed at the longitudinal ends of the skeleton such as actuation levers or proximate to the attachment points of rings such as springs wrapped around ring bases, and transversely protruding elements which are not fixed to rotate with the elongated portion such as a cover-attachment fastener wrapped about and rotatable about the elongated portion.
One object of loose-leaf binders, which is related to both the skeleton and the cover, is minimization of the "footprint " of the binder. The footprint of a binder is the area that is covered by any part of the binder when the binder is placed upon a generally flat surface. Minimizing a binder's footprint during use efficiently utilizes desk, table, or lap space.
A substitute product, the spiral notebook, specifically addresses this object by letting users flip the front cover and forward pages perfectly flat beneath the back cover and latter pages. However, spiral notebooks do not permit the easy addition or removal of pages.
Conventional loose-leaf binders have a very large footprint because, during use, the front cover is open 180 degrees relative to the back cover. This large footprint causes these binders to be cumbersome during use. Furthermore, if the front cover and forward loose-leaves are flipped behind the back cover and latter loose-leaves of a conventional binder, the forward and latter loose-leaves do not lie flat against the front and back covers, respectively. Large stress is exerted on some loose-leaves causing them to tear out of the binder and the airfoil shape of the stack of forward loose-leaves, front cover, back cover, and latter loose-leaves does not provide a flat writing surface. Furthermore in this case, writing on the topmost loose-leaf is difficult as the stack of loose-leaves bends and springs back under the shifting weight of a writing hand and wrist.
In the prior art, there have been attempts to minimize the footprints of loose-leaf binders during use while eliminating the problems mentioned above for conventional binders. However, each of these attempts has had some failing including: (1) sacrifice of a desired feature, (2) only partial achievement of this functionality, and (3) addition of undesirable characteristics.
The failings of known loose-leaf binders to minimize binder footprints are principally the result of (1) the large transverse cross-section dimensions of spines of known skeletons, (2) the methods employed to attach covers to skeletons, and (3) the design of the covers.
The first main cause of these failings, the large transverse cross-section dimensions of loose-leaf binder skeleton spines, has generally resulted from a common objective of skeletons, the ability to simultaneously open and close all rings of a skeleton via a simple actuation mechanism. SOCRA, which is used herein to describe these skeletons, is an acronym for Simultaneously Openable/Closeable Rings Actuation.
Conventional loose-leaf binders have SOCRA skeletons with spines having transverse cross-sections with major and minor dimensions wherein the large major dimension is built into the perimeter of the rings whereas the minor dimension is substantially radial to the center of the rings. Binder skeleton spines have traditionally had a transverse cross-section with a ratio of major to minor dimensions greater than two.
Conventional loose-leaf binders have a front cover attached to a middle cover which in turn is attached to a back cover. The SOCRA skeleton is rigidly fixed to the middle cover or back cover via rivets.
Exemplary dimensions of conventional loose-leaf binder covers in the market are as follows:
Front and Back Cover Thickness Middle cover Thickness 2 mm 2 mm 3 mm 4.5 mm 4 mm 5 mm
Typical dimensions of conventional loose-leaf binder skeletons in the market are as follows:
 Ring Outer Diameter Ring Prong Thickness Skeleton Spine Width 13.5 mm 1 mm 10 mm 21 mm 2 mm 16 mm 32 mm 2.8 mm 25 mm 75 mm 3.5 mm 50 mm
A ring outer diameter differs from its corresponding ring inner diameter by two ring prong thicknesses. Skeleton spine width is the major transverse cross-section dimension of a binder skeleton spine. The widths of skeleton spines are affected and constrained by the SOCRA mechanism employed and ring prong thickness. Note that as ring size increases, prong thickness increases to handle the stronger forces acting on the rings. Because ring prongs are commonly riveted into plates in conventional skeletons, as ring prongs increase in thickness, the skeleton spine width also must increase to secure the thicker prongs. The smallest conventional binders in the market which are small pocket binders have skeleton spine widths that are still 10 mm thick. Because of the thinness of cover segments and thickness of SOCRA skeleton spines in the prior art, the prior art generally teaches away from embedding of a SOCRA skeleton spine in a binder cover.
The large transverse cross-section of known SOCRA skeleton designs has led to the orientation of the transverse cross-section such that the major dimension is substantially radial to the center of the rings in an attempt to minimize the binder footprint. However, this orientation has made attachment to the cover more difficult which in turn has led to the use of loose-leaf front and back covers with no middle cover disposed therebetween. Such configuration exposes the rings and the ends of the loose-leaves leaving both less protected and makes the binder cumbersome to handle and less attractive. In such a known binder, the skeleton creates an awkward lump, thwarting the object of a flat writing surface, when positioned within a stack of loose-leaves or when positioned between the front cover and back cover after the front cover is flipped around against the back cover. U.S. Pat. No. 3,190,293 to Schneider, U.S. Pat. No. 4,904,103 to Im and U.S. Pat. No. 2,331,461 to Dawson are examples of such known binders.
Alternatively, to minimize binder footprints, some loose-leaf binders have independently-openable rings. In some of these loose-leaf binders, the back cover pivots about the thin skeleton spine and the front cover hangs loose-leaf on the rings, but there is no middle cover joining the front cover to the back cover. These designs make insertion and removal of loose-leaves tedious. Also, the exposed rings are unattractive and the loose-leaves are less protected. U.S. Pat. No. 659,860 to Schild and U.S. Pat. No. 2,268,431 to Slonneger are examples of such binders.
Yet another problem with known attempts to build a minimal-footprint binder are inadequate ring shapes having varying loose-leaf capacity when these binders are open 360 degrees versus when they are closed. This variation in capacity results from inclusion of the skeleton among the loose-leaves in one position but not in the other. U.S. Pat. No. 4,904,103 to Im is an example of such a binder.